Because she dreads going home to find nothing changed with her mother, Gifty starts spending more time in the lab. She prefers the familiar boredom of her work to boredom at home, which is painful since she’s always hoping it will change. Han also spends a lot of time in the lab, driven by his work.
The lack of connection with her mother at home leads Gifty to spend more time at the lab, where her relationship with Han can grow. Because they're both driven by their research work, this is an especially important relationship for Gifty, since it shows that science and friendship aren’t mutually exclusive.
Gifty is allergic to the mice. She remembers a time in the first year of her experiments when she had itchy rashes from them. One day, she scratched one while Raymond cooked food for breakfast. She had asked him to stop her, but when he did, she resented being told what to do with her own body. He suggested seeing a doctor, even though he thought she was “funny about…medicine” after she refused painkillers for strep throat. If prescribed, Raymond said he would take “the good stuff.” Gifty didn’t answer but drove to her lab weeping.
As Gifty spends more time at the lab (and with Han), her allergy to the mice reasserts itself. This leads to a memory of Raymond, who reminded her to stop scratching her mouse-induced rash one day at breakfast. Both in the reminder (which Gifty asked for) and his offer to make her breakfast, Raymond offers her intimacy, but she refuses it. She’s peeved at the reminder, and she refuses to eat the food he wants to make her. At another moment, she’s hurt by Raymond’s casual approach to potentially addictive drugs. But, since she hasn’t been willing to tell him anything about her family, she’s holding him responsible for things he couldn’t possibly know.
Gifty is more careful about handling the mice and washing her hands, and she rarely gets the rashes anymore. But staying in the lab for too long affects her thoughts, and she begins to wonder “What’s the point?” One mouse is so addicted to the Ensure that he can’t learn to stop pressing the lever and he has developed a psychosomatic limp in anticipation of the shocks. Gifty is attached to this mouse. But she’s bothered by the fact that the human question of purpose—which both science and religion attempt to address—is so hard to answer.
Now Gifty’s response to overexposure at the lab is philosophical rather than physical. The hopelessly addicted mouse reminds her of her hopelessly addicted brother, and because she couldn’t help or save him when she was a child, she doubts her ability to make a difference or change the mouse’s behavior now. The fears and doubts she experiences as a scientist recall the fears and doubts that characterized her religious beliefs, offering yet another reminder of the similarity between the two systems in Gifty’s mind.